WO2005070643A1

WO2005070643A1 - Photopolymeric and/or polymeric encapsulation in integrated circuits with direct soldering and the respective process to obtain it

Info

Publication number: WO2005070643A1
Application number: PCT/BR2004/000183
Authority: WO
Inventors: Milton Flávio de MACEDO
Original assignee: Global Id South America Ltda
Priority date: 2004-01-27
Filing date: 2004-09-23
Publication date: 2005-08-04

Abstract

An encapsulation process, which may be photopolymeric or polymeric, to protect the electrical conductors (3) of the feeding coil (4). The electical conductors (3) are soldered by point compression to die (1) of the transponder, and immersed in a photpolymerizable resin (6), and exposed to ultraviolet light radiation (7), to obtain a polymer (8). The device may be encapsulated between two plastic films to form the transponder. Another option includes, after the step of soldering, immersing the die (1) in a polymerizable resin (6), heating in a heating oven to dry and obtain the polymer (8) and finally encapsulated between the plastic films.

Description

PHOTOPOLYMERIC AND/OR POLYMERIC ENCAPSULATION IN INTEGRATED CI RCUITS WITH DIRECT SOLDERING AND THE RESPECTIVE PROCESS TO OBTAI N IT The present description refers to an invention patent application for an innovative process covering a photopolymeric system and/or, be it the need, a polymeric system which, in both procedures, has in a whole the purpose to promote the physical integrity and protection between an electrical conductor and an electronic component, pertaining to the electronics field, more precisely used for the protection and connection between an electrical conductor and a DI E, or an integrated circuit with no encapsulation, i . e. a small miniaturized silicon blade containing transistors, diodes or other electronic components, able to perform various complex functions, including the transmission and reception of radio frequency signals. Original disposition was given to the circuit, aiming to improve the production system over other systems traditionally in use in the field. We therefore have an especially projected and developed process to bring huge practicality to the use and optimization in construction, besides offering better quality to the electronic device to be protected, exempting knowledge which may go much beyond the traditional experience as already found in the field in which processes linked to the electronic and chemical industries are employed. It is also an object of this application to present an innovative procedure disposition under low costs for its industrial execution, but added to safety, economy and practical use requirements, thus offering users of said technical field an additional option in the market of similars which, as opposed to the usual application of the available processes, offers numerous possibilities of acceptance by the consumer market, perfectly appropriate for the use and protection of connection points of electronic circuits and similars. STATE OF THE ART As widely known, electronic components notoriously highlight as basic devices to build numerous electronic circuits, being developed each day to meet the growing demand of the electronic industry. The integrated circuit or chip is a basic component for the development of circuits, since it is the most important component to memorize tasks, commands and information to be performed by the circuit, being said component able to process data, following a previously determined set of instructions, interpreting them and co-relating them so to activate response protocols, which control the activities to which it was designated. An example of these various applications of miniaturized chip is the manufacture of transponders, sender-receiver sets intelligently replying by radio frequency to an identification message originated by a signal sent by a given radio frequency sender source, being said technology called RFID. Within the class of transponders, we can find systems fed by means of a coil, composed by a conductor geometrically located around a common center, so to become similar to a helical curve or a set of spirals, able to receive electromagnetic waves and convert them into electrical energy, enough to feed the chip connected to the coil. As known, notably by experts in the art, in the case of transponder manufacture, it is imminently difficult to solder the coil conductor wire and the chip. One of the methods to connect electrical conductors over the chip is performed by thermal compression, i. e. by means of point compression with the help of a punch applied against the electrical conductor, which is supported over the surface to be connected, thus causing interaction between metals to adhere the electrical conductor over the surface. However, since the electrical conductor is filamentous and small-sized, it can suffer scourings or fatigue caused by the pressure of the filament over chip edges. To solve this problem, there are various processes to encapsulate and immobilize soldering dots between the chip and its corresponding electrical conductors, but in most cases they produce very rigid systems, causing the rupture of the contact in the conductor itself, which becomes unfeasible in case of transponder manufacturing . Furthermore, practiced encapsulations are costly processes since they involve a series of chip preparation steps to receive immobilization, being many times hot processes, which drying time requires the exposure of the chip for long periods under high temperature and with no appropriate protection, compromising the operation of said chip, since they are sensible to quick thermal changes. OBJ ECTS OF TH E I NVENTION Aiming to supply the market with a process to protect the connection between electrical conductors and the respective chip, the process at issue was developed, as immersion in photopolymerizable resin by ultraviolet radiation, resulting in a pellicle granting considerable protection to the connection point, with no prejudice to the flexibility of the system as a whole. Optionally, the initial encapsulation may be practiced by using lacquer resin or similar, being drying made in an oven at a previously set up temperature in a polymerization system, thus considerably reducing costs over the photopolymerization system. Both options keep, however, the same principles of the process as a whole to recover wires and protect the transponder, which is finally passed by encapsulation between two plastic films, after the immersion/exposure steps to ultraviolet radiation and/or application of lacquer/quick drying in an oven. Anyway, the mentioned steps have the purpose to protect the connection point between the chip and the coil, bringing to the market a new option, linking considerably reduced added costs, with no prejudice to the production levels, thus resulting in an extremely positive cost/benefit ratio. For better understanding of the invention, the process is disclosed in further detail below, according to the attached drawings, in which we can read: Figure 1 - upper view of the DI E connected to electrical conductors; Figure 3 - side view of the DIE connected to the electrical conductors, covered by the protecting polymer, in which the final covering , as already stated, presents the same visual and physical/functional conditions for both photopolymerization and polymerization systems. Figure 4 - side view of the DI E during the thermal compression process after taking the excess of material . Figure 5 - upper perspective view of the DI E connected to electrical conductors of the coil. Figure 6 - upper perspective view of the transponder covered with resin and plastic pellicle, keeping the same visual and physical characteristics for both photopolymerization encapsulation and polymerization encapsulation . Figure 7 - side cut view of the transponder detailing the contour of the DI E covered with polymer, keeping visual and physical characteristics for both photopolymerization encapsulation and polymerization encapsulation. Figure 8 - schematic upper perspective view of the transporting mat of the coil connected to the DIE for the covering step by the photopolymerizable resin. Figure 9 - schematic side view of the transporting mat of the coil connected to the DI E to be covered with photopolymerizable resin, showing the impregnation and photopolymerization steps. Figure 10 - schematic side view of the coil connected to the DI E to be covered with resin, e. g . lacquer, showing the impregnation and photopolymeriation steps in a heated oven, resulting in a DI E covered with polymer. According to the attached drawings, the PHOTOPOLYMERIC AND/OR POLYMERIC ENCAPSULATION IN I NTEGRATED CI RCU ITS WITH DIRECT SOLDERI NG AND THE RESPECTIVE PROCESS TO OBTAI N IT object of the present invention patent application is constituted of different steps, in which the DIE (1 ) of the transponder (2) receives solder from the electrical conductors (3) of the feeding coil (4) over it, being said solder imposed by the action of point compression with the help of a punch (5), being said integrated circuit (1 ) subsequently immersed in an appropriate photopolymerizable resin (6). After said immersion step (6), the DI E (1 ) is passed to an ultraviolet light exposure step (7) to form an involving polymer layer (8), which will protect the connection from electrical conductors (3) as properly said, avoiding disruptions by pressure, fatigue or scouring around the edge of said DI E (1 ), being the set passed to the encapsulation step between two plastic films (9) to form the transponder (2). Optionally, but keeping the principles and purposes of protection and maintenance of the properties for the transponder (2), the process counts on a corresponding procedure, in which said DI E (1 ), after receiving solder from electrical conductors (3) of the feeding coil (4) over it, as a consequence of the point compression with the help of the punch (5), is immersed in a polymerizable resin (6), preferably lacquer, to recover electrical connectors (3), being the DI E (1 ) subsequently passed to the drying step in a heating oven (10) to form an involving polymer layer (8). Said layer (8) will equally protect the connection of electrical conductors (3) over the DI E (1 ), thus avoiding disruption of the wires due to pressure, fatigue or scouring around the edge formed after the encapsulation of the transponder (2) formed between both plastic films (9). The time for which the DI E (1 ) is submitted to said heating oven (10) is lower than one minute, preferably 15 seconds, for the applied resin to become a polymer (8), being the temperature in the oven (10) preferably lower than 150 °C. Said polymerization encapsulation then arises as an option linking (just like the initial photopolymerization system) extremely efficient technical conditions resulting from a study disclosing the possibility of quick drying at a considerably reduced cost, bringing in a very good cost/benefit ratio. Therefore, in functional terms, both via photopolymerization or polymerization systems, the present process enables to handle the transponder (2) with no worries about the disruption of the connection of electrical conductors (3), caused by their scouring by compression over DI E (1 ) edges. Therefore, the transponder (2) can be inserted within objects with no worries about the disruption of their components, since the polymer (8) inserted around the DIE (1 ) efficiently absorbs the mechanical efforts to which it is submitted, especially under aggressive environments, besides not interfering in its data emission-reception system via radio frequency.

Claims

CLAI MS 1 . PHOTOPOLYMERIC ENCAPSULATION IN INTEGRATED CI RCU ITS WITH DI RECT SOLDERI NG AND THE RESPECTIVE PROCESS TO OBTAIN IT, in which the DI E (1 ) of the transponder (2) receives solder from the electrical conductors (3) of the feeding coil (4) over it, being said solder imposed by the action of point compression with the help of a punch (5), being said integrated circuit (1 ) subsequently immersed in an appropriate photopolymerizable resin (6), with the DI E (1 ) following, after the immersion step, for exposure to ultraviolet light radiation (7), thus obtaining a polymer (8) in a layer involving the DI E (1 ), being the set subsequently passed to the encapsulation step between two appropriate plastic films (9) to form the transponder (2).

2. POLYMERIC ENCAPSULATION IN I NTEGRATED CI RCU ITS WITH DIRECT SOLDERI NG AND THE RESPECTIVE PROCESS TO OBTAIN IT, in which the DI E (1 ) of the transponder (2) receives solder from the electrical conductors (3) of the feeding coil (4) over it, being said solder imposed by the action of point compression with the help of a punch (5), being said integrated circuit (1 ) subsequently immersed in a polymerizable resin (6a), preferably a lacquer, to recover the wires (3), being the DI E (1 ) taken to passage by a heating oven (10) to form the polymer (8) in a layer involving the DI E (1 ), being the set subsequently passed to the encapsulation step between two appropriate plastic films (9) to form the transponder (2).

3. POLYMERIC ENCAPSULATION IN INTEGRATED CIRCUITS WITH DIRECT SOLDERI NG AN D THE RESPECTIVE PROCESS TO OBTAI N IT of claim 2, in which the residence time at the heating oven (10) is lower than one minute. 3. POLYMERIC ENCAPSULATION IN INTEGRATED CI RCU ITS WITH DI RECT SOLDERI NG AN D THE RESPECTIVE PROCESS TO OBTAI N IT of any of claims 2 and 3, in which the residence time at the heating oven (10) is preferably of about 15 seconds.

3. POLYMERIC ENCAPSULATION IN I NTEGRATED CI RCU ITS WITH DI RECT SOLDERI NG AN D THE RESPECTIVE PROCESS TO OBTAIN IT of any of claims 2, 3 and 4, in which the temperature of the heating oven (10) is preferably lower than 150 °C. 1. PHOTOPOLYMERIC AND/OR POLYMERIC ENCAPSULATION IN INTEGRATED CIRCUITS WITH DIRECT SOLDERING AND THE RESPECTIVE PROCESS TO OBTAIN IT of any of claims 1 and 2, which includes the protection, by the involving polymer layer (8), of the connection of electrical conductors (3) as properly said, thus avoiding the occurrence of disruptions by pressure, fatigue or scouring around the edge of said DIE (1 ), thus enabling to handle the transponder (2) with no worries about the disruption of the connection of electrical conductors (3), caused by their scouring, by compression over the edges of the DIE (1 ).